Synchronizing control



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CAT-Tommy's Patented Ma 18, 1943 UNITED STATES PATENT OFFICE 2,319,218' SYNCHRON IZIN G CONTROL George Forrest Woodward Governor C a corporation of Illinois Application January 2, 1941, Serial No. 372,939

' (also-97) 16 Claims.

and inexpensive in construction, light in weight,

operable were. wide speed range, and adapted for adjustment from a remote point 01' control.

Another object is to provide a novel means for effecting manual adjustment of the speed of a plu-' rality of power units within a comparatively wide range and automatic synchronizing of the slave unit within a comparatively narrow'range.

A further object is to provide such a speed matching control combined with means to indicate when the slave unit is adiusted for operation at a predetermined point within its automatic speed range.

The invention also out of the foregoing objects.

Other objects and advantages oi the invention will become apparent rrom'the following detailed description taken in connection with the accompanying drawings, in which Figure 1 is a schematic view and wiring diagram resides in the novel construction of the control which facilitates carrying I of a synchronizing control embodying the present I invention. t

Fig. 2 is a plan section taken along the line 2-2 of Fig. 4.

Figs. 3 and 4 are sections taken "along the lines 3 3 and 4-4 of Fig. 2.

Fig. 5 is a section taken along the'line 5-5 of Fig. 3.

r Fig. 6 is a schematic view and wiring diagram showing the application of the invention to more than two power units.

While the improved synchronizing system is applicable to the control of various kinds of multiple unit power generators under widely varying operating conditions, it is especially adapted for and will be describ d herein as applied to the synchronization of a group or internal combustion understood, however, that I engines. It is to -be do not intend to limit the invention by such disclosure nor to the particular construction .of the governor and power units but aim to cover all modifications, alternative constructions and uses falling within the spirit and scope of the invention as expressed in the appended claims.

As illustrated'in the two unit control shown in Fig. 1, th invention provides for individual manual adjustment of master and slave engines M and S for operation at any desired speed, and for automatic adjustment of the slave unit speed to of pressure fluid and the adjustment member permitting Drake, Rockford, Ill., assignor to omnany, Rockford, Ill.,

match the selected speed of the master unit. The speeds of the engines M and S are controlled by individual governors Ill and I. These may operate directly on the engine throttles or, when the engine is arranged to drive an aircraft propeller as shown, the engine speed may be controlled by adjusting the propeller pitch. In the latter case, hydraulic pressure controlled by .the governor is applied to a servo motor l2 which aotuates a cam l3 by which the pitch of the propeller I4 is changed.

The governors are including a head It which rotates of similar construction each IS on the upper end of a sleeve in a bore ll of a hollow casing 18. Flyballs in the form of hell-cranks l9 are pivoted at 20 on the head and have arms bearing upwardly gainst the outer race of an anti-friction bearing 2!, the inner race of which fits on a valve rod 22 and is urged downwardly by a coiled speeder spring 23 acting on a collar 24 fast on the upper end of the rod. Through a suitable gear connection. 25, the lower end of the sleeve 3 is driven from the crankshaft 26 of the associated engine.

The valve rod 22 has a land 21 which cooperates with ports 28 in the sleeve It to control the flow through a. conduit 29 to the forward end of the servomotor, the rear end of which is connected by a pipe 29" to the engine lubricating system-and therefore maintained under pressure by the usual pump 29 Fluid is drawn from the engine lubricating system lby a booster pump 30 and delivered at an valve chamber above the land 27, pressure being maintained constant loaded by-pass valve 3 l With this'arrangement, the hydraulic pressure applied to the servomotor will be varied in accordance with the position of the valve stem, which position is determined by the speed of the engine of the speeder spring 23. An speed raises the pilot valve the flow of fluid from the head end of the servo cylinder and into the rod end resulting in an increase in the propeller pitch. Conversely, a decrease in speed below the governor setting results in the admission of presthe delivery by a spring increase in engine ernor speed setting, the upper end of each speeder increased pressure to the spectively with the stator I fast on a shaft 38 which projects outwardly from the governor casing and carries a pulley around which is wrapped a cable 40 extending to an-operating lever 4| at the main control station. A coiled compression spring 46 is interposed between the ring 32 and a block 45 seated in the upper art of the cover. This spring counteracts the speeder spring 23 and prevents the latter from moving the adjusting mechanism to the lowest speed setting in the event of breakage of the cable 40.

The apparatus thus far described is typical of that now in common use for maintaining constant speed operation of airplane engines and for selecting different speed settings for the individual engines. The present invention contemplates an auxiliary adjustment by means of which the speed setting of one engine, S in this instance, may be varied automatically over a narrow range whereby the speed of this slave engine may be matched with that of the master engine M. To this end, a secondary independently adjustable speed spring 42 is incorporated in the governor of the slave engine to supplement the action of the main spring 23. tHerein, the spring B2 is a coiledspring concentric and disposed within the spring 23 with its lower end threaded onto the upper end 13 of the valve rod 22. The upper end is threaded onto and thereby'fastened to the lower end of a rack bar it slidable in the block 65 endwise along the axis of the valve stem. The teeth of the rack mesh with a pinion M on a shaft d8 journaled in the casing and rotatable to adjust the rack endwise and thereby vary the compressive or tensile stress exerted by the spring 52. (The rack movement is limited in opposite directions by suitable means such as the end 59 of the casing cover and by engagement of a lug 50 on the rack with the block 55.

Automatic adjustment of the spring 42 is effected by a motor 5| housed in the casing cover 35.. The motor is a so-called differential Selsyn comprising a stationary two pole three phase stator 52 and a three phase two pole rotor 53 excited from independent sources of three phase alternating current which produce rotating fields in both the rotor and the stator. The rotor is fast on a shaft 54 of an associated commutator switch 55. Through a pinion 56 and a gear 51, the torque of the motor is amplified and applied to the shaft 38. Thus, when the stator and rotor windings are energized at different frequencies, the motor will operate in a corresponding direction to raise or lower the rack 45 and thus extend or compress the spring 42 so long as the speed difference persists or until one of the limit stops is encountered.

To compare their speeds, the engines M and S are equipped with small permanent magnet gen-' erators 58 and 59 each driven from the crankshaft 28 of its associated engine. The generators may be of the type disclosed in Patent No.

2,071,536 and are arranged for connection reand rotor windings of the differential motor 5i. For this purpose, the terminals of the generators are extended to the stator and rotor windings respectively through having interposed therein a multiple pole single throw switch 62 adapted for manual operation from -the same point of control as the speed adjusting levers 4|.

When the switch ,62 is closed,'the synchronizing control will be operative. If the engines are operating at the same speeds, the frequencies of conductors 6B and BI the two alternating current sources will be identical and there will be no mechanical movement of the motor shaft 48. When the speeds are dilferent, the frequencies of the generated currents will vary proportionately and the differential shaft will turn at a rate proportional to the difference in frequency and in a direction determined bywhioh frequency is greater. The auxiliary spring 42 of the governor H is thus adjusted to change the speed of the setting and thereby bring the engine S back into synchronism with the master engine.

It. will be observed that the spring 42 may act in compression or in tension and thus add or subtract its force and that of the main speeder spring. I 'The characteristics of the springs are such that the speed adjustment may be varied over a major portion of the range by means of the main spring 23 and over only a fraction 01 the range, for example ten per cent, by adjustment of the spring 42. In any case, this latter range, although comparatively narrow, is sufiicient to enable normal deviations of the slave engine speed from that of the master engine to be corrected.

In order to equalize the speed deviations of the slave engine that may be corrected for on each side of the speed of the master engine, means is provided for indicating when, by preliminary manual adjustment of the main spring 23' before the automatic control is operative, the stress in the spring 42 is zero and the'speed settings of the two governors are identical; that is, the auxiliary spring stress is zero. As herein shown, this means comprises an electric signal lamp 63 responsive to movement of the adluster for the spring t2 and arranged to be lighted when the adjuster is at the middle of its range of movement. This is accomplished by a cam actuated switch 64 interposed in a conductor 65 which connects .the ungrounded contact 66 of the switch to the lamp, which preferably islocated at the remote point of control adjacent the levers dl. As shown, the insulated switch contact is on an arm 61 pivoted at 68 within the governor casing. The arm overlaps and is urged by a spring 69 toward an insulating disk 10 and a smaller metal disk H both fast on the shaft 48 so that the metal disk is grounded. The disk in has a fiat 12 on onesideangularly disposed so as to be presented to the contact 66 when the rack 44 is at the middle of its range, thereby permitting the contact to engage the metal contact disk H as shown in Figs. 1 and 5. As the shaft moves in either direction from this position, the insulating disk cams the contact away from the disk I! thereby deenergizing the lamp. In this way, the switch 64 will be closed in only one position of the shaft 44. A hand switch 13 may be opened to prevent unnecessary draining of the battery 15 when the synchronizing control is not in use.

The operation of the synchronizing control above described in the normal flight of an airplane will be as follows. The take ofi is made with the switch 62 open and the engines under gized to turn the shaft 48 counter-clockwise 42 to its limit thereby the main spring 23 and eflecting an increase in the speed setting of the slave engine governor. As the speed setting of the main spring continues to increase under manual control and the cumulative setting due to the combined action of the two springs exceeds that of the master engine, the operation of the diflerential motor will be reversed decreasing the compression of the auxiliary spring 42 progressively to compensate for increases in the manual setting of the slave engine governor. During this action, the speed of the slave engine will be slightly above that of the master depending on the rate at which the manual adjustment is eiIected. Finally, when the stress of the main spring has been increased manually to a value corresponding to speed setting of the master governor spring, the stress of the auxiliary spring will have been eliminated. At this point, the fiat side of the insulating cam It will be presented to the switch contact 55 and the latter will move into contact with the disk II closing the switch 64 and lighting the lamp 63.

- The signal advises the pilot that the aitomatic governor adjuster is now in the middle of its operating range and thus conditioned to correct for equal deviations of the slave engine speed in opposite directions from that 'of the master.

It will beobserved that reverse action of the compressing the spring adding to the force of motor will take place if the speed oi! the slave engine is above that of the master as the time.

the synchronizing control is rendered operative. In such a case, the rack bar 44 would be raised, thus placing the spring 42 under tension which decreases progressively as the speed setting of the manual adjuster is decreased. When effect of the spring 42 has been eliminated, the light signal is elIective, thereby indicating that the automatic control is conditioned for proper operation. If, with the'control thus conditioned, the speed of the slave engine falls below that of the master, the resulting frequency difierence causes operation of the motor 5| in a direction to raise the rack 44 and thereby place the spring 42 under tension. This force subtracts from that of the spring 23 thereby increasing the speed setting of the governor until the speed of the slave engine again equals that of the master. The speed of the slave engine is changed in the same way in response to speed diiferences resulting from changes in the speed of the master engine relative to that of the slave unit. By

' varying the tension in the spring 42, the automatic control is capable of compensating automatically for speed decreases below that of the master up to one-half of the total range of adjustment determined by the characteristics of the auxiliary spring.

Assuming now that the speed of the slave engine rises above that of the master, reverse adjustment of the auxiliary springwill take place.-

That is, the motor 5| will turn in the opposite direction to lower the rack 44 and place the spring 42 under compression. This force is added to that of the main spring 23 decreasing the slave engine speed until this has matched that of the master. X

The synchronizing control is, of. course, disabled preparatory to landing. If thisis done when the signal lamp 53 is lighted, the adjustor for the auxiliary spring will remain at the center of its range while the slave engine is on manual control. Then, if the two engines are synchroalternator.

nized by manual adjustment before again shitting to automatic control, the manual adjustment of the slave engine as above described to light the lamp will be unnecessary.

The automatic synchronizing control as above.

described is especially adapted for use with two power units and on airplanes because the equipment required is reduced to a minimum. It will be observed that all or the parts are of light weight and comparatively inexpensive in construction and yet are extremely reliableiinoperation. The control is operable over the entire speed range of the controlled power units and may easilybe rendered operative and inoperative at will.

If desired, the number of power units controlled may be increased and all or any number of these made selectable as the master. Fig. 6 shows a system applied to four engines A, B, C and D having two units B and C either one of which may be selected as the master, the other then being a slave unit. The control is generally similar to the two motor system previously described except for an increased capacity 01' the generators 59 and 59 of the master engines and the addition of manually operable two position switches and 8| for determining which 01' the engines B or C shall act as the master. Also, since, each master unit may operate as a slave unit, their governors are equipped, with differential motors and auxiliary springs 42 adjusted by such motors.

Referring now to Fig. 6 in which the indicating lamps 63 and the manual switches therefor are omitted, the capacity of the alternators 58 and 59 for the units B and C is made sufficient, triple in the present instance, to energize one winding of the diiferential motors 5| of each of the three engines which it may serve as master. Eachdiiferential motor may be disabled by opening a manually operable switch 62 and the associated engine withdrawn from the automatic control. Manually operable switches 82 are provided in the conductors leading from the master erators 59 and 58 for interrupting or resuming the automatic control 'for all of the engines.

The selector switches 80 and 8| have a common two position actuator 83 which when positioned as shown conditions the circuits for operation of the engine C as the master. Thus, the output from the alternator 59 is delivered through conductors 84 to the rotors of the motors 5|, lil and 5| and both windings of the motor 5| are disconnected. Through the switch ll, the conductors 84 are connected to the rotor 53 and the stator 52 is energized by the alternator 59 As a result, the stators of the slave engines A, B and D are energized from the associated alternators while the rotors are excited by the master The operation is as previously described, the speed of each slave unit being matched automatically with'that or the master. The automatic control for all of the slave engines may be disabled simply by opening the switch 82.

To makeengine B the master, the switch actuator 83 is shifted to its other position. This disconnects both windings of the master motor 5|", connects the alternator 59 to the conductors 84 and conditions the motor 59 for energization of its rotor and stator from the alternators 59 and 59 respectively. With the control thus conditioned, the speeds of theslave units A, C and gen- . latively to determine D are adjusted automatically to match that of the master unit B. It'will of course be apparent that provision may be made for using only one of the engines as the master. Or with appropriate changes in the switches, the number of engines selectable as the master may be increased.

I claim as my invention:

1. A control for matching the speed of one power unit with that of a master unit having, in

" combination, an adjustable governor controlling the speed of said master unit, a second adjustable governor controlling the speed of said second unit including two individually operable speed adjusting means coacting cumulatively to determine the governor speed setting, manually operable means controlling the adjustment of one of said adjusting means, electromagnetic means controlled selectively in accordance with differences between the speeds of said units, means actuated by said electromagnetic means to actuate said other adjusting means, and means to indicate the position of said se ond adjusting means approximately midway between the limits of its operating range.

2. Acontrol for matching the speed of one power unit with that of a master unit having, in combination, a governor controlling the speed of said first mentioned unit including two individu ally adjustable speeder springs coacting to determine the governor speed setting, manually operable means controlling the adjustment of one of said springs, electric motor means variably energized in accordance with differences in the speeds of said units, means actuated by said motor means to adjust the stress of said second spring, and means for indicating the adjustment of said second spring approximately midway between the limits of its stressrange.

3. A a control for matching thespeed of one power unit with that of a master unit having, in combination, a governor controlling the speed of said first mentioned unit including two individually adjustable speeder springs coacting cumuthe governor speed setting, manually operable means controlling the adjustment of one of said springs; electromagnetic means variably energized in accordance with differences in the speeds of said units, means actuated by said electromagnetic means to adjust the stress of said second spring, a switch actuated by said last mentioned means when said second spring is adjusted to a predetermined degree, andindicating means controlled by said switch.

; 4. A control for matching the speed of one power unit with that of a master unit having, in combination, manually adjustable means controlling the speed of said master unit, means including two individually adjustable springs coacting to determine, according to their combined stresses, the speed of the other unit, manually operable means controlling the adjustment of one of said springs, electromagnetic means differentially operable in accordance with the speed of said master unit, means actuated by said electromagnetic means to adjust the stress-of said second spring, and means actuated in unison with speed changes of said second spring and operable to indicate a predetermined adjustment of the latter;

'5. A control for matching the speed of one power unit with that of a master unit having, in combination, a governor controlling the speed of said first mentioned unit including two individually adjustable speed adjusting means coacting to determine the governor speed setting, manually operable means controlling the adjustment 01' one of said adjusting means, means automatically operable to actuate the other adjusting means and correct for difi'erences in the speeds of said units, and means operable to indicate a predetermined speed setting of said automatic means irrespective of the setting of said manually operable means.

6, In a synchronizing control, a governor having two independently movable speed adjusting means coacting cumulatively to determine the governor speed setting, and means operable to indicate the position of one of said adjusting means at a predetermined point in its operating range irrespective of the adjustment of the other means.

7. In a synchronizing control, a governor having two independently movable speed adjusting means coacting cumulatively to determine the governor speed setting, automatically operable means for actuating one of said adjusting means, and means operable automatically to indicate a predetermined speed setting of said last mentioned means irrespective of the adjustment of the other means.

8. In a synchronizing control, a governor having two independently movable speed adjusting means coacting cumulatively to determine the governor speed setting, automatically operable means for actuating one of said adjusting means, and means operable automatically to indicate the setting of said last mentioned means substantially midway between the limits pf its operating range irrespective of the setting of the otheradjusting means. V

9. In a synchronizing control, the combination of a governor automatically controlling the speed of a power unit and having rotary fiyballs, two

coiled springs concentrically arranged and opervariably loading said last mentioned means, the other of said springs acting in tension or compression, and means operable automatically to vary the character and degree of stress in said other spring selectively.

10. In a synchronizing control, a governor having a manually adjustable main speeder spring, and an auxiliary speeder spring selectively adjustable to add to or subtract from the force of said first spring whereby the speed setting of the governor is determined by the cumulative loading of the two springs.

11. Inasynchronizing control, a governor having a coiled speeder spring adjustable (to vary the governor speed setting, a second coiled spring coacting with said first spring to determine the speed setting, and means operable selectivelyto I place said second spring under tension or comthe action'of said centrifugal weights thereon,

respective movable abutments for 'said springs movable independently of each other, and respective means independent of each other for moving saidabutments, the weaker of said springs being connected to its movable abutment and for matching the speed of two a secondary governor adjusting member movable independently. of said spring, an auxiliary single coil spring in parallel with said first spring producing a force variable selectively by movement of said member and arranged to add to or subtract from the force of the first spring or to exert substantially no force either on said adjusting member or on said iiyballs when the member member or to be energized selectively in accordance with the speeds of said prime movers and cause movement of said member in one direction or the other away from said neutral position while permitting of movement of the member to such means is deenergized.

14. In a control for matching the speed of one prime-tmover against mover, the combination of a the speed of said first mentioned prime mover and having rotary centrifugal weights, first and second adjusting. members'movable independentmeans adjustable by member.

position when the power that of a master primegovernor controlling said auxiliary resilientmeans being 09- position, and power means adapted for one of said one posi- A erable by movement of the second member in opposite directions from said neutral position to respectively increase and decrease the total resilient force on said weights.

15. In a control for matching the speeds oi two prime movers each having a governor with rotary flyballs and a speeder spring acting thereon and selectively adjustable to vary the governor speed-setting, the combination of arotary differential motor energized selectively in accordance with the speeds of both of said motors, a second spring'associated with one of said governors and acting on the flyballs thereof in paral-.

lel with the speeder spring, means providing a driving connection between said .motor and said second spring whereby the latter is stressed differentially either to add to ing a neutral position in supplemental force is exerted either on said connection or on the iiyballs of its governor whereby the speed settings of both governors are determined soleiy by the adjustments of these individual speeder springs.

16. In a control for matching the speeds of two prime movers, the combination of a governor prime movers having rotary flyweights and a main speed adjuster exerting a resilient force on said weights, an auxiliary independently movable speed adjusting member, power means operable to move said member in opposite directions from a neutral position in response to rises and falls in the speed of one prime mover relative to that of theother, and a spring comprising a single resilient coil connected between said member and said flyweights and adapted to be placed either under tension or compression to exert oppositely acting iorceson said flyweights, the character of said spring stress being determined by the direction of movement o1- said member away from said neutral position.

' GEORGE mnars'r DRAKE.

or subtract from the I 

